clang/lib/Lex/MacroArgs.cpp

   1 //===--- MacroArgs.cpp - Formal argument info for Macros ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the MacroArgs interface.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/Lex/MacroArgs.h"
  14 #include "clang/Lex/LexDiagnostic.h"
  15 #include "clang/Lex/MacroInfo.h"
  16 #include "clang/Lex/Preprocessor.h"
  17 #include "llvm/Support/SaveAndRestore.h"
  18 #include <algorithm>
  19
  20 using namespace clang;
  21
  22 /// MacroArgs ctor function - This destroys the vector passed in.
  23 MacroArgs *MacroArgs::create(const MacroInfo *MI,
  24                              ArrayRef<Token> UnexpArgTokens,
  25                              bool VarargsElided, Preprocessor &PP) {
  26   assert(MI->isFunctionLike() &&
  27          "Can't have args for an object-like macro!");
  28   MacroArgs **ResultEnt = nullptr;
  29   unsigned ClosestMatch = ~0U;
  30
  31   // See if we have an entry with a big enough argument list to reuse on the
  32   // free list.  If so, reuse it.
  33   for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
  34        Entry = &(*Entry)->ArgCache) {
  35     if ((*Entry)->NumUnexpArgTokens >= UnexpArgTokens.size() &&
  36         (*Entry)->NumUnexpArgTokens < ClosestMatch) {
  37       ResultEnt = Entry;
  38
  39       // If we have an exact match, use it.
  40       if ((*Entry)->NumUnexpArgTokens == UnexpArgTokens.size())
  41         break;
  42       // Otherwise, use the best fit.
  43       ClosestMatch = (*Entry)->NumUnexpArgTokens;
  44     }
  45   }
  46   MacroArgs *Result;
  47   if (!ResultEnt) {
  48     // Allocate memory for a MacroArgs object with the lexer tokens at the end,
  49     // and construct the MacroArgs object.
  50     Result = new (
  51         llvm::safe_malloc(totalSizeToAlloc<Token>(UnexpArgTokens.size())))
  52         MacroArgs(UnexpArgTokens.size(), VarargsElided, MI->getNumParams());
  53   } else {
  54     Result = *ResultEnt;
  55     // Unlink this node from the preprocessors singly linked list.
  56     *ResultEnt = Result->ArgCache;
  57     Result->NumUnexpArgTokens = UnexpArgTokens.size();
  58     Result->VarargsElided = VarargsElided;
  59     Result->NumMacroArgs = MI->getNumParams();
  60   }
  61
  62   // Copy the actual unexpanded tokens to immediately after the result ptr.
  63   if (!UnexpArgTokens.empty()) {
  64     static_assert(std::is_trivial_v<Token>,
  65                   "assume trivial copyability if copying into the "
  66                   "uninitialized array (as opposed to reusing a cached "
  67                   "MacroArgs)");
  68     std::copy(UnexpArgTokens.begin(), UnexpArgTokens.end(),
  69               Result->getTrailingObjects<Token>());
  70   }
  71
  72   return Result;
  73 }
  74
  75 /// destroy - Destroy and deallocate the memory for this object.
  76 ///
  77 void MacroArgs::destroy(Preprocessor &PP) {
  78   // Don't clear PreExpArgTokens, just clear the entries.  Clearing the entries
  79   // would deallocate the element vectors.
  80   for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
  81     PreExpArgTokens[i].clear();
  82
  83   // Add this to the preprocessor's free list.
  84   ArgCache = PP.MacroArgCache;
  85   PP.MacroArgCache = this;
  86 }
  87
  88 /// deallocate - This should only be called by the Preprocessor when managing
  89 /// its freelist.
  90 MacroArgs *MacroArgs::deallocate() {
  91   MacroArgs *Next = ArgCache;
  92
  93   // Run the dtor to deallocate the vectors.
  94   this->~MacroArgs();
  95   // Release the memory for the object.
  96   static_assert(std::is_trivially_destructible_v<Token>,
  97                 "assume trivially destructible and forego destructors");
  98   free(this);
  99
 100   return Next;
 101 }
 102
 103
 104 /// getArgLength - Given a pointer to an expanded or unexpanded argument,
 105 /// return the number of tokens, not counting the EOF, that make up the
 106 /// argument.
 107 unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
 108   unsigned NumArgTokens = 0;
 109   for (; ArgPtr->isNot(tok::eof); ++ArgPtr)
 110     ++NumArgTokens;
 111   return NumArgTokens;
 112 }
 113
 114
 115 /// getUnexpArgument - Return the unexpanded tokens for the specified formal.
 116 ///
 117 const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
 118
 119   assert(Arg < getNumMacroArguments() && "Invalid arg #");
 120   // The unexpanded argument tokens start immediately after the MacroArgs object
 121   // in memory.
 122   const Token *Start = getTrailingObjects<Token>();
 123   const Token *Result = Start;
 124
 125   // Scan to find Arg.
 126   for (; Arg; ++Result) {
 127     assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
 128     if (Result->is(tok::eof))
 129       --Arg;
 130   }
 131   assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
 132   return Result;
 133 }
 134
 135 bool MacroArgs::invokedWithVariadicArgument(const MacroInfo *const MI,
 136                                             Preprocessor &PP) {
 137   if (!MI->isVariadic())
 138     return false;
 139   const int VariadicArgIndex = getNumMacroArguments() - 1;
 140   return getPreExpArgument(VariadicArgIndex, PP).front().isNot(tok::eof);
 141 }
 142
 143 /// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
 144 /// by pre-expansion, return false.  Otherwise, conservatively return true.
 145 bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
 146                                      Preprocessor &PP) const {
 147   // If there are no identifiers in the argument list, or if the identifiers are
 148   // known to not be macros, pre-expansion won't modify it.
 149   for (; ArgTok->isNot(tok::eof); ++ArgTok)
 150     if (IdentifierInfo *II = ArgTok->getIdentifierInfo())
 151       if (II->hasMacroDefinition())
 152         // Return true even though the macro could be a function-like macro
 153         // without a following '(' token, or could be disabled, or not visible.
 154         return true;
 155   return false;
 156 }
 157
 158 /// getPreExpArgument - Return the pre-expanded form of the specified
 159 /// argument.
 160 const std::vector<Token> &MacroArgs::getPreExpArgument(unsigned Arg,
 161                                                        Preprocessor &PP) {
 162   assert(Arg < getNumMacroArguments() && "Invalid argument number!");
 163
 164   // If we have already computed this, return it.
 165   if (PreExpArgTokens.size() < getNumMacroArguments())
 166     PreExpArgTokens.resize(getNumMacroArguments());
 167
 168   std::vector<Token> &Result = PreExpArgTokens[Arg];
 169   if (!Result.empty()) return Result;
 170
 171   SaveAndRestore PreExpandingMacroArgs(PP.InMacroArgPreExpansion, true);
 172
 173   const Token *AT = getUnexpArgument(Arg);
 174   unsigned NumToks = getArgLength(AT)+1;  // Include the EOF.
 175
 176   // Otherwise, we have to pre-expand this argument, populating Result.  To do
 177   // this, we set up a fake TokenLexer to lex from the unexpanded argument
 178   // list.  With this installed, we lex expanded tokens until we hit the EOF
 179   // token at the end of the unexp list.
 180   PP.EnterTokenStream(AT, NumToks, false /*disable expand*/,
 181                       false /*owns tokens*/, false /*is reinject*/);
 182
 183   // Lex all of the macro-expanded tokens into Result.
 184   do {
 185     Result.push_back(Token());
 186     Token &Tok = Result.back();
 187     PP.Lex(Tok);
 188   } while (Result.back().isNot(tok::eof));
 189
 190   // Pop the token stream off the top of the stack.  We know that the internal
 191   // pointer inside of it is to the "end" of the token stream, but the stack
 192   // will not otherwise be popped until the next token is lexed.  The problem is
 193   // that the token may be lexed sometime after the vector of tokens itself is
 194   // destroyed, which would be badness.
 195   if (PP.InCachingLexMode())
 196     PP.ExitCachingLexMode();
 197   PP.RemoveTopOfLexerStack();
 198   return Result;
 199 }
 200
 201
 202 /// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
 203 /// tokens into the literal string token that should be produced by the C #
 204 /// preprocessor operator.  If Charify is true, then it should be turned into
 205 /// a character literal for the Microsoft charize (#@) extension.
 206 ///
 207 Token MacroArgs::StringifyArgument(const Token *ArgToks,
 208                                    Preprocessor &PP, bool Charify,
 209                                    SourceLocation ExpansionLocStart,
 210                                    SourceLocation ExpansionLocEnd) {
 211   Token Tok;
 212   Tok.startToken();
 213   Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
 214
 215   const Token *ArgTokStart = ArgToks;
 216
 217   // Stringify all the tokens.
 218   SmallString<128> Result;
 219   Result += "\"";
 220
 221   bool isFirst = true;
 222   for (; ArgToks->isNot(tok::eof); ++ArgToks) {
 223     const Token &Tok = *ArgToks;
 224     if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
 225       Result += ' ';
 226     isFirst = false;
 227
 228     // If this is a string or character constant, escape the token as specified
 229     // by 6.10.3.2p2.
 230     if (tok::isStringLiteral(Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
 231         Tok.is(tok::char_constant) ||          // 'x'
 232         Tok.is(tok::wide_char_constant) ||     // L'x'.
 233         Tok.is(tok::utf8_char_constant) ||     // u8'x'.
 234         Tok.is(tok::utf16_char_constant) ||    // u'x'.
 235         Tok.is(tok::utf32_char_constant)) {    // U'x'.
 236       bool Invalid = false;
 237       std::string TokStr = PP.getSpelling(Tok, &Invalid);
 238       if (!Invalid) {
 239         std::string Str = Lexer::Stringify(TokStr);
 240         Result.append(Str.begin(), Str.end());
 241       }
 242     } else if (Tok.is(tok::code_completion)) {
 243       PP.CodeCompleteNaturalLanguage();
 244     } else {
 245       // Otherwise, just append the token.  Do some gymnastics to get the token
 246       // in place and avoid copies where possible.
 247       unsigned CurStrLen = Result.size();
 248       Result.resize(CurStrLen+Tok.getLength());
 249       const char *BufPtr = Result.data() + CurStrLen;
 250       bool Invalid = false;
 251       unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);
 252
 253       if (!Invalid) {
 254         // If getSpelling returned a pointer to an already uniqued version of
 255         // the string instead of filling in BufPtr, memcpy it onto our string.
 256         if (ActualTokLen && BufPtr != &Result[CurStrLen])
 257           memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
 258
 259         // If the token was dirty, the spelling may be shorter than the token.
 260         if (ActualTokLen != Tok.getLength())
 261           Result.resize(CurStrLen+ActualTokLen);
 262       }
 263     }
 264   }
 265
 266   // If the last character of the string is a \, and if it isn't escaped, this
 267   // is an invalid string literal, diagnose it as specified in C99.
 268   if (Result.back() == '\\') {
 269     // Count the number of consecutive \ characters.  If even, then they are
 270     // just escaped backslashes, otherwise it's an error.
 271     unsigned FirstNonSlash = Result.size()-2;
 272     // Guaranteed to find the starting " if nothing else.
 273     while (Result[FirstNonSlash] == '\\')
 274       --FirstNonSlash;
 275     if ((Result.size()-1-FirstNonSlash) & 1) {
 276       // Diagnose errors for things like: #define F(X) #X   /   F(\)
 277       PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
 278       Result.pop_back();  // remove one of the \'s.
 279     }
 280   }
 281   Result += '"';
 282
 283   // If this is the charify operation and the result is not a legal character
 284   // constant, diagnose it.
 285   if (Charify) {
 286     // First step, turn double quotes into single quotes:
 287     Result[0] = '\'';
 288     Result[Result.size()-1] = '\'';
 289
 290     // Check for bogus character.
 291     bool isBad = false;
 292     if (Result.size() == 3)
 293       isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
 294     else
 295       isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'
 296
 297     if (isBad) {
 298       PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
 299       Result = "' '";  // Use something arbitrary, but legal.
 300     }
 301   }
 302
 303   PP.CreateString(Result, Tok,
 304                   ExpansionLocStart, ExpansionLocEnd);
 305   return Tok;
 306 }